Jantunam nar janm durlabham, tath: punstam tatho vipratwam

Means to be born as a human being is very difficult, and if somebody is born as a human being, then to be a Braahman is difficult.
When a soul takes birth in an Uttam Braahman family he comes with three loans -- Rishi Rin,  Dev Rin,  and Pitri Rin

These following comments are taken from opinion of different Gurus based on Ved, books and scriptures.

The religious traditions associated with the death ceremonies, Shraaddh can be understood at different levels. They may be understood as a religious mandate based purely on Shraddhaa or faith based on reason and trust. The traditions can also be understood by appreciation of the scriptures as a means of knowledge for things that are beyond the scope of human intellect to know.

The Ved are looked upon as a means of knowledge in regards to matters that are beyond the scope of knowledge of a human mind to arrive at by itself. A human mind can gain knowledge of various matters directly be sense perception and indirectly by inference based on sense perception. An average person cannot directly perceive what happens to an individual after his death.

That the Ved are a means to know the unknown, naturally leads one to the question about the validity of the Ved as a means of such knowledge. Many religious traditions establish the authenticity of their scripture by calling upon the faith of an individual unquestioningly accept what they say. Vaidik traditions establishes the authenticity of the Ved.

The Ved talk about various ends and means to accomplish them in pursuit of means and ends, there can be known means for achieving known ends, unknown means for achieving known ends and unknown means for achieving unknown ends. Clearly one cannot have known means for achieving unknown ends. In the first case, the known means for achieving known ends are available to man. In the second case, there are desired ends for which either the means are unknown or the means that are known to accomplish the given end do not achieve their purpose due to unknown factors that are beyond human control. In this instance the Ved provide the means in the form of specific karmas, rituals that address the unknown factors, eg by understanding the words of Ved one can attain self knowledge (unknown factor, the essential nature of Oneself). In the third case, the Ved identify unknown ends such as heaven and the unseen results of Karm, A-drasht, in the form of merit (Punya), and in the form of demerit (Paap), with respect to the moral order Dharm.

A Hindu's life is also guided by an understanding of the universal order of Dharm and A-Dharm and the laws of Karm. He believes that a person's existence does not begin with death of a physical body. There is an indweller in the body called Praanee or Jeev who manifests in a given body in order to experience the prior Karm Phal (results of the actions of his previous lives).

The scriptures also point out that time itself is experienced differently by different forms of life. In the Vaidikc tradition time has been understood as essentially not having an absolute reality. In fact, a person experiences time differently during waking, dream and deep sleep states. Thus the number of days experienced by individuals on Earth is not experienced in the same manner by a Pret, or Pitri or Dev and so on. One does not know for certain, in terms of our concept of time when a Jeev will assume another birth of a physical body. It is for this reason that when oblations are performed for ancestors , one invokes three generations of ancestors to represent all of them. There is no such thing as completely getting over or resolving the death of a loved one. Still there are rare occasions when a person is unable to overcome the grieving process.

Samyak kriyate yen Karmana iti Sanskaar:

Bodhayaan Pitrimedh Sookt states (3.1.4)
Jaat sanskaaren Lokaamabijayati Mrit sanskaaren Amum Lokam
[Means by the sacrament of Jaatkarm (Sanskaar performed after birth) on gains desirable ends in this world; and by the sacraments performed upon death, one gains s desirable world hereafter.]

The individual responsible for and expected to perform the final sacrament on behalf of the deceased, is his son (the eldest if he has more than one). If the deceased was bereft of a son then his grandson (born of his daughter), or a male relative connected to him in the patrilineally such as his brother's son, or a relative belonging to the same Gotra or connected to him patrilineally (Sa-Pind) has the privilege of performing the ceremonies. This custom is not because of bias against daughters but is the reflection of the patriarchal nature of of most of Hindu society. Additionally it reflects the customary manner by which most rituals are performed, which is that a man performs the ritual with the consent and the participation of his wife and other woman in the family. A deceased person's wife can also perform the ceremonies directly with a priest as proxy. If there is no relative, his teacher Aachaarya, student or even a friend are qualified to do so. For one who has no relative or friends the King is obliged to perform the necessary religious ceremonies. The final ceremonies are described in the Taittireeya Aaranyak portion of Krishn Yajur Ved, Grihya Sootra of Bodhayaan, Bharadwaaj, Ashwalayan and Hiranyakeshee. The Garud Puraan describes in detail.

Kritwa tu Pushkaram Karm Janaat Vapyajanaatam
Mrityu: Kaal vaasam Praapya Naram Panch Twam Gatam
Dharmaadharm Samaayuktam Tam Lok Moh Samaavratam
Deheyam Sarv Gotraani Divan Lokan sa Gachchhatu

Having performed known and unknown actions for attaining prosperity, having gained timely death and resolved the physical body into five elements, having concluded a life of desires and connected to Dharm and A-Dharm, may you proceed to heavenly realm.

Prehi prehi pathibih purvebih yatra nah purve pitri: pare yah
sSangachaswa pitribhih samyamena ishta poorten parame vyoman

The deceased in the form of Pret is implored to go forth, leaving behind all Paap, on the ancient path on which our ancestors have gone.

Prathame Ahni triteeye va saptame navame tathaa
Ashti sanchayanam kaaryam dine tad gotra jaih saha
[Means on the first, third, seventh, or ninth day collection of the ashes and remains to be performed along with relatives belonging to ones Gotra.]

The pile of ashes and remains are separated and anointed by sprinkling milk on it while chanting Mantra and the ashes are immersed in river such as Ganges or ocean.